Electric lighting system



Oct. .13, 1936. i B. DAVIS EdT AL 2,057,184v

ELECQRIC LIGHTING SYSTEM Filed Aug. l, 1935 iNVE TORS Patented Oct. 13,1936 AUNITED STATES PATENT oI-Flclaz ELECTRIC LIGHTING SYSTEM BasilDavis, Brockley Hill, Stanmore, George Application August 1,

1933, Serial N0. 683,172

In Great Britain August 4, 1932 6 Claims.

This lnventionrrelates to electric lighting systems adapted to giveillumination in a plurality of colours, one object being the provisionof improved, convenient and economical apparatus for controlling thedimming of electric lights. Al-

though applicable in other spheres the invention is particularly usefulfor ballroom lighting.

According to the invention, in an electric lighting system, intended forexample for ballroom lighting, a negative booster and automatic boostingmeans are adapted to automatically and periodically dim a lamp or groupof lamps. Preferably the electric lighting, system here involved isadapted to give illumination in a plurality of colours eithersimultaneously or separately and the negative boosting means is providedand so arranged as to sequentially dim a lamp group or are driven by acommon device such as an electric' motor. According to a further featureof the invention it should be observed that during operation thedifferent lamp circuits may individually be completed or interrupted,but means are provided whereby a lamp circuit can not be interrupted orcompleted except when 'the booster has substantially dimmed the lamp orlamps thereof. Preferably also the switching means, for instance a drumswitch is adapted to control the circuits of the lamps or lamp groups insuch a way that during each complete revolution of the drum switch eachlamp circuit is associated with the booster when the latter is eiectiveto dim the lamp or lamps connected in the circuit, is then renderedindependent of the booster when the latter is ineffective to dim thelamps, and then is ineffective to dim the lamps and is finallydissociated from the booster when the latter is eiective to dim thelamps. Furthermore a lamp circuit may be/controlled so that at times itis operatively associated with the booster, While at other times it isassociated with a power supply independent of the booster and during thetransfer the booster ora part thereof is shunted or short circuited. Insuch arrangement, the shunting or short circuiting is preferablyeffected in stages. Moreover it is preferably arranged that prior to thetransfer of a lamp circuit from operative association with the boosterto association with an independent power supply, a eld Windingreassociated with the booster when the latterof the booster is given asmall reversed excitation.

The 4accompanying diagrammatic drawing shows one arrangement of circuitsand .devices for 5 carrying out the invention.

Referring to the drawing, the arrangement shown comprises three sets ofelectric incandescent lamps I, 2, 3 which are assumed respectively, forexample, to be of red, blue and green colours. The positive and negativesupply bus-bars are shown respectively at 4 and 5 and one side of eachof the lamps in the groups I, 2, 3 is connected to the positive bus-bar4 by lines 6a, 6b, 6c. The groups of lamps I, 2, 3 are, on the sideremote from the bus-bar 4 connected through individual on-off switches'I and individual fuses 8 to leads 9,. I0, vI I, common to the lamps ofthe respective groups, the leads 9, I0, I I being connected respectivelyto contacts on one side of the main group contactors I2, I3, I4. Thecontact on the other side of each group contactor is connected throughleads I2a, I3a, I4a. to the movable contactors I5a, I6a, I'Ia of themultiple pole double throw switches I5, I6, or I1. The movablecontactors I5a, I6a, Ila of the switches I5, I6, I'I are respectivelyadapted to cooperate with contacts I8, I9, 20 when moved to the left andcontacts 22, 23, 24 when moved to the right, the contacts I8, I9, 20 ofwhich are connected by leads I8a, I9a, 20a to a common lead 2l connectedto lthe negative bus-bar 5.

Auxiliary contacts 25, 26, 2l connected by leads 54, 55, 56 to leads ia,ISa, 20a and thence by lead 2i to the negative bus-bar 5, are arrangedto cooperate with the central movable contactors |517, i617, IIb onswitches I5, I6, II and are adapted to be closed on closure of theassociated contacts I8, I9, 20. Similarly, auxiliary contacts 28, 29, 30arranged to cooperate with movable contactors I5b, I6b, I'Ib andcontacts 3i, 32, 33 arranged to cooperate with movable contactors I5c, I6c, Ic are adapted to be closed on the closing of the associatedcontacts 22, 23, 24,V when the movable contactors of switches I5, I6, I1are moved to the right.

The contactors I2, I3, I4 are provided with operating coils 34, 35, 36,connected through economy resistances 31, 38, 39 which by lines 40a,49h, 40e are connected through fuses 4Ia, 4Ib, 4 I c to the positivebus-bar 4. Associated with and closing at the same'time as the maincontactors I2, I3, I4 are auxiliary contactors 42, 43,44 each -havingone cooperating contact connected by leads 34a, 35a, 36a with therespectiveoperating coil 34, 35, 36 on the side remote from theconnecting lines 40a, 40h, 40e, and the other contact connected by leads42a, 43a, 44a, with movable contactors |5c, |6c, |1c. Also connected toleads 34a, 35a, 36a and extending from the same sides of the contactorclosing coils 34, 35, 36 are tumbler switches 45, 46, 41 connected bylines 48, 49, 50 to the respective central movable contactors |5b, |6b,|1b of switches 5, i6, |1 which contactors are adapted to cooperate withthe respective contacts 25 and 28, 26-and 29, and 21 and 30.

The contacts 25, 26, and 21 of switches I5, |6, I1, as previouslyexplained, are connected by lines 54, 55, 56 to the common'line 2|leading to negative vbus-bar l5. However, contacts 28, 3| of switch l5;29,32 of switch |6; 30, 33 of switch |1 are connected respectively bylines 51, 58; 59, 60; 6|, 62 to contact fingers 64, 65; 66, 61; 68, 69of a drum switch controller 63. The drum switch controller 63 ispreferably provided, in addition to the contact fingers 64 to 69, withcontact fingers 10 to 8| inclusive. The contact fingers 64 to 8| of thedrum switch controller are adapted to be engaged respectively by drumswitch segments asfollows: 64 by 83; 65 by 85; 66 by 86; 61 by 81; 68 by89; 69 by 90; 10 by 82; 1| by three parts 9|, 92 and 93; 12 by threeparts 94, 95 and 96; 13 by 91; 14 by 98; 15 by |00 (shown divided); 16by 11 by |02 and |03; 18 by |04 and |05; 19 by |06 and |01; 80 by |08;8| by |09, ||0 and The contacts 22, 23 and 24 of the switches |5, I6 and|1 are connected by lines ||2, ||3 and ||4 y to the drum switch fingers19, 18, 11 respectively and will be seen on the drawing, the finger 19is connected by a lead to the finger 16; the finger 18 by a lead |6 tothe finger 15, and the finger 11 by a lead ||1 to the finger 14.

The controller or drum switch 63 is adapted to be rotated through theintermediary of gearing (not shown) by a regulator motor having anarmature I8 and a shunt field winding I9, which, through suitablegearing, also drives, in a. counterclockwise direction, a regulator arm|20, one end of which engages a slip ring |2|, while the other end, asthe arm is rotated, is adapted to cooperate with circularly arrangedcontacts |20a of a regulator, the circuit connections of which will behereinafter described. It should be noted that the gearing connectionsbetween the regulator arm |20 and the drum switch 63 are to be soarranged that the arm |20 performs three revolutions in the time thatthe drum switch performs one. In the arrangement, as shown in thedrawing, the drum switch 63 is in its starting position.

In the regulator the contacts |20a over which the regulator arm |20moves, are divided into six sets. Regulator set A lying between endcontacts |22 and |23 has all intermediate contacts |20a connected totappings on a potentiometer resistance winding |24. Regulator set Bhaving end contacts |25 and |26 has all intermediate contacts |20aconnected to corresponding contacts in regulator set A. Regulator set Chaving end contacts |21, |28 has all the contacts |20a in the setconnected one with another in series. Regulator set D having endcontacts |29, |30 has all its conregulator set C and by a line |35 withthe end contact |23 of the regulator set A. Regulator set F having endcontacts |36, |31 has its contacts |20a connected with each other inseries and the end contact |36 is connected to the end tapping ontheresistance winding |24.

One side of the armature ||8 and the shunt field winding ||9 of theregulator motor driving the regulator arm |20 and the drum switch 63, isconnected through `line- |40 and a fuse |38 to a line |39a connected tothe negative bus-bar 5. The armature ||8 is connected, on the sideremote from the line |39a, |40 with a line |4| connected to one contact|42 of a normally open having a movable contact member |52 and a trip ncoil |53.

Reverting now to the regulator member constituted by the rotatingregulator arm |20 and the regulator contact sets A to F, it will be seenthat the slip-ring |2| is connected by a line |54 with the one end ofthe shunt field coil |56 of a booster |55 having an armature |51 andseries field coil |58. The booster |55 is driven by a booster motor|59having an armature |60 and a shunt field coil |6|. The other end ofthe shunt coil |56 of the booster |55 is connected by a line |62 to theend contact |21 of the regulator contact set C. The end contact |22 ofregulator set A is, connected by a lead line |63 with the left contact|50 of the overload trip switch |5| and by a branch line |64 to anauxiliary contact |65 onbooster series field coil |58 is connected byaline |1| to the contact |1|a of a contactor |12,

having a closing coil |13, the other contact |12a of which by the line|39 is connected to the line 2| which leads to the negative bus-bar 5.The other side of the booster series field coil |58 and one side of thebooster armature |51 are connected by a line |14 to the contact finger8| on the drum switch 63. The sideof the boster armature |51 remote fromthe. line 14 is connected by a line |15 with the contact finger 80 onthe drum-switch 63.

Also connected to the common side (line |14) of the booster series eldcoil |58 and the booster armature |51 is a. shunting resistanceA |16 theend of which is connected by a line |11 with the contact finger 12 onthe drum switch 63; and a tapping |16a"on the resistance v|16 isconnected by a line |18 with the contact finger 1| on the drum switch63.

One side of the booster motor armature |60 and the shunt field winding|6| of the booster motor |59 are connected by a line |19 to a contact|80 of the isolating switch |66 and when the said switch |66 is closed,the contactor member 18| of the switch closes on contact |80 andcompletes the circuit, contactor |8| by the lines |82, |39 and 2| beingconnected to the negative bus-bar 5. The other end of the booster motorarmature |60 is connected by a line |84 to a series resistance |85having its other end and a number of tappings connected to contacts on abooster motor 'starting contactor; the entire resistance |85 beingadapted to be connected in series with the overload trip switch I| whichby a line |90 is connected to a contact |9| of the isolating switch |66,the contacter |92, of which by lines |93 and |94 is connected to thepositive bus-bar 4.

The booster contacter set |86, I 81, |88 is provided with a clesi'ngcoil |95 which closes contactor I 86' first, and is of the type in whichthe successive closing of contactors |81, |88 is preferably determinedby time-delay mechanism (not shown). The motor starting contacterassembly |86-|88 is also provided with an auxiliary contacter |96,adapted to close with contacter |86: and a changeover contacter |91,normally closed en contacts |98B, but when operated slmultaneously withcontacter |81 is adapted to close on contacts I98A.

The operating coil |95 of the booster contacter assembly |86; |81, |88,|96, |91 is adapted to be energized en the closing of. a contacter |99previded with an operating coilv200 connected by'4 leads 20|, 202between one end of the armature I|8 of the regulator lmotor and thenegative bus-bar 5. The energization of the booster. contacter operatingcoil |95 is effected when the regulator motor has attain-ed a reasonablespeed at which time the contacter |99 closes to complete the circuitover lines |4| I4Ia, contacter |99, line 203, operating coil |95, line204, contacts |98B through contacter |91, line 205, control circuitfuse`206 and lines |82, |39, 2|, to the negative bus-bar-5. Theregulator motor (armature |I8) starts immediately upon depression of thestart switch |43 since it is then energized by a circuit from bus-bar 5through line |39a, fuse |38, line'I40, the armature I|8 and shunt II9then over the line I 4I, closed start switch |43, line |45, stop switch|48, line |49, overload trip switch I 5I, line |64, contact |65,contacter |65a of isolatingswitch |66, line 209 te positive busbar 4 byline |94. vWhen the regulator motor attains the prearranged speed, thecontacter |99 operates to close the circuit of the booster contactoroperating coil |95 thusclosing contactors |86 and |96. The closing ofcontacter |96 makes a maintenance circuit through coil |95 for thebooster contacter from negative bus-barv 5, lines 2| and |39, over line|82, fuse 206, line 205, contact maker |91 and vcontacts |98B, line 204,closing coil |95 of the booster contacter, contacter |96,'1ines 208,|45, contact |46, stop switch contacter |48, contact |41, line|49,.contacts |50 and contacter |52, line |64, contact |65 of isolatingswitch, contacter I65a, line 209, and line |94 to the positive bus-bar4. After the predetermined time delay set by the mechanism operating thebooster contacter (|86-|91), which is sufcient to ensure that thebooster motor |59 has run up to speed (the eld I6I ofthelbooster motoris completed en closing of the contacter |86 over the line 2|0), thesuccessive closing ef the contactors |81 and |88 having cut out theresistance |85 in steps, the changeover contacter |91 in the meantime ismoved away from contacts |98B to thereby insert an economy resistance2II in the maintenance circuit through the `operating coil |95 of thebooster contacter over lines 2I2, 2|3, connected respectively to lines204 and 206. `At the same time contacter |91 by making with the contacts|98A, completes a circuit from the negative bus-bar 6 over lines2|,-I39, |82, 201, fuse 206, line 205, contact maker |91 (in lowerposition), contacts I98A, line 2I4, economy resistance 2I5, operatingcoil |13 of conl tactor |12, line 2|6, contacts |50, contacter |52, line|64, contact 65 of isolating switch` |66, line 209, line |94 te positivebus-bar 4, which results in the contacter |12 beingclosed and thuscompletes thev output circuit from the booster |55 through the serieseld |58, lines |69, I1I, contacts |1|a, |12a and contacter |12, lines|39 and 2| to negative bus-bar 5, which it will be under-l 2I1 isprovided which is energized over the lines 2I8, 2|9 and fuse 220, line201a, lines |39 and 2| to the negative bus-bar 5 en completion of thebooster motor circuit upon the closing of contacter |86 oi' the boostercontacter.

In order that a better understanding of the invention may be gained,there will new be described the complete operation of the arrangement.

It is assumed that the desired lamps ofv the banks I, 2, 3 have beenselected by closure of the corresponding switches 1. The nature of theillumination desired from the lamps (i.e. periodically dimmed or steady)is determined by the multiple pole 4double throw switches I5, I6, I1;for instance when these switches are in the left position, that is whencvontactors |5a, I6a, |1a are on contacts I8, I9, 20, the lamps will be,on

closure of the group contactors I2, I3, I4, connecteddirectly betweenthe bus-bars 4 and 5, over lines 6a, 6b, 6c from positive 4, lamp groupsI, 2,

3, lines 9, I0, II, contactors I2, I3, I4, lines |2a,

|3a, |4a, contactors |5a, I6a, I1a, contacts I8, I9, 20lines |8a, I9a,20w, to common return line 2| to negative bus-bar 5. When, however, theswitches I5, I6, I1 are in the right hand position, in which thecentacters I5a, IBa, |1a are on contacts 22, 23, 24 the lamp groups willbesuccessively dimmed by the negative boost from the booster in a manneras will be hereinafter described.

The closure of the desired `group contacter, I2, I3, I4, will new lbedescribed with reference to contacter I2, since the operation is similarfor the remaining contactors I3 and I4. When the double threw switchesI5, I6, I1 are in the left position, the contacter |2 is closed by meansof the tumblerswitch 45. When this switch 45 is closed a circuit iscompleted from the positive bus-bar 4, through the control circuit fuse4|a, over line a, economy resistance 31, contacter coil 34, tumblerswitch 45, line 48, contacter |5c en contact 25 (which were closed withthe closing of the switch |5 in the left position) line 54, line |8a,line 2| to negative bus-bar 5.4 In this manner the operating coil 34 isenergized to close 'the contacter I2, and contacter I2 will remainclosed until the switch is opened, or until the circuit through contact25 is opened by opening the double throw switch I5. In this position theillumination will be steady. 7^

If, on the other hand, it is desired tohave all three groups of lamps I,2,43 periodically dimmed in prearranged rotation, the switches I5, I6,I1

are moved to their right hand positions in which` switch |66 should bealso closed. The start" pletion of a circuit from the negative bus-bar 5over line I39t'., fuse |39, line |40, through the armature |I9 and fieldI |9 of the regulator motor, over the line I4I, contact |42 and contactmember |43, contact |44, line |45, contact |49, "stop". contact member|49, contact |41, line |49, overload trip switch |52 and its contacts|50, line |94, contact |95,l (isolating switch |99) contacter I95a, line209 and line |94 to positive bus-bar 4.

' The regulator motor is thus set in rotation, and after it has speededup and the back E. M. F.

across its armature I I9 has built up, the operating4 coil 200 of thecontacter |99 is energized to closev its contacter |99 and thus tomakethe closing circuit Irom I4I'and line I4Ia, through |99, line 203,booster contacter coil |95, line 204, contacts |99B `and contacter |91,line 205, fuse 209, lines 201,

|92, |39 and 2| to the negative 5, thus operating the coil |95 of thebooster motor starting contacter assembly (I99-I91), which will causeenergization of the booster motor the circuit being from positivebus-bar 4 through lines |94, |93, contacter |92, of isolating switch|66, contact |9I, line |90, overload coil |53, line |99, contactor |99(of thebooster contacter) resistance |95, line |94, booster motorarmature |90, and forshunt iield coil |9I from resistance |95 throughline 2I0, line |19, contact |90 and contacter |9I, of isolating'switch|99, lines |92, |39, 2|, to negative busbar 5. After the time delaydetermined by the delay mechanism associated with the booster contacterassembly, and when the booster motor is substantially up to speed, thechangeover contacter |91 of the booster contacter is operated, that is,the contacts |98B are opened to insert the economy resistance 2I| in thebooster contacter operating coil |95 circuit, and contacter |91 makeswith its contacts |99A and thereby completes the circuit of theoperating coil |13 between lines 2|4 and 205, as ha's previously beendescribed, which causes the contacter |12 to close.

For the simplification of the further description, it is assumed thatwhen the contacter |12 closes, the drum-switch 93 and the regulatorassembly are in the position shown in the drawing and that the regulatorand drum switch rotate in the directions indicated by the respectivearrows. Further, it will be 'noted that the drum switch is divided intosix sections, indicated by dotted lines and numberedgi to 9, the line Ibeing the same on each side of the drum development shown. By theclosing oi contacter |12 a circuit is immediately completed 'from thepositive busbar 4, through the control circuit fuse 4|c and line 40e,through the economy resistance 39, operating coil 39, closed tumblerswitch 41, line 50, contacter I1b, contact 30, line 9|, contact finger99,

interconnected drum segments 99, 90, 91, 96, `95,-

holding circuit for contactors I4 and 44 which is completed overcontacter 44 from line 36a through line 44a, contacter I1c, contact 33,line 92, centact finger 69, drum segment and then over the same segmentsand lines, as just described, over which the closing circuit wascompleted.

Upon the drum switch 63 moving into positionv to bring section 3 underthe contact fingers, a closing circuit for contacter I3 for lamp group 2is set up, through the engagement of contact ilnger 99 and drum segment99, which contacter I3 isV thereafter heldA closed over a maintenancecircuit through contact ringer 91 and drum segment 91. At the same time,the contact finger 11 engages the drum segment |02 and completes acircuit `from the positive bus-bar 4 through the group of lamps 3,(green) over line II, contacter I4, contactor I1a and contact 24 ofchangeover switch l I1,'llne II4, line II1, contact finger 11, drumsegment |02, drum segment |09, contact lingers 90,

line |15, through the booster set |55 (armature I 51 and series coil|59) and line I1I, contacter |12, line |39 and line 20 to the negativebus-bar 5. The regulator will, however, be in the position shown, sinceit is performing three revolutions to one revolution et the drum;accordingly the voltage across the booster shunt tleld |59 is a maximum,and the booster will be yielding its maximum output, in opposition tothe line supply. The lampsl in bank 3 (the green lamps) will accordinglybe dim. At the same time contactiinger 12 (at right of drum) is engagingdrum segment 495 (section 3) so that the shunting effect of theresistance |16 willbe a minimum.

Continued rotation of the regulator arm |20' Y however in thecounter-clockwise direction, as indicated by the arrew,will result inthe voltage across the shunt ield |56 of the booster being reduced,until when the .rotating arm |20 engages contact I2 3,at the end ofregulator set A, the voltage across 'the shunt tleld is zero; duringthis time the green lamps accordingly increase in brilliance. The arm|20 from contact |23 moves onto contact |31 (end contact of regulatorset F) and a reverse current is applied to the booster shunt ileld |56for a short |16a over line |19; and at the same time contact finger 9|engages drum segment IIO and thus the booster is short circuited,-asexplained later.

Next, on engagementl of the regular arm |20 with the contact |30 a smallreverse current is passed through the shunt field |56 of the boosterset. The contact finger 14 at this time engages cuit `for the greenlamps 3, from the positive drum segment 99 and thus completes a lampcirbus-bar 4 through the lamps` 3, the group con- -I tactor I4, doublethrow switch I1, contact 24, line II4, line ||1,.contact finger 14, drumsegment 90, drumsegment 91, contact nger 13, line |99,

line |1|, contacter |12, line |39, line 2| and negative bus-bar 5. Atthe same time the booster |55 is short-circuited over linesl |14, |15 atcontact ilngers-9| and 00 by the engagement with these Acontact fingerswith connected drum segments I|0 and |09. Also simultaneously with theshort circuiting oi' the booster |55, disengagement of drum segment fromcontact nger 12l and the engagement of contact ilnger 1I with drumsegment 93, makes a change in the resistance |16, so that the current4through the series field |59 is readjusted to a value which will allowthe sh'ort circuit on the booster |55 to be opened without a suddentvoltage change. The

greenf lamps 3 then stay at full brilliance while the drumswitch 93movies into position in section 4 and will remain so until they arelater transferred to drum segment |03.

On moving into position in section 3, the concsl tact ringer 18 engageswith the drum segment |05 and hence the blue lamps in bank 2 are put incircuit in series with the booster which is then giving its maximumoutput, the ,blue" lamps 2 are thus at first dim, but during the nextrevolution of the regulator (remembering that the regulator is makingthree revolutions to one.

for the drum) the blue lamps are brought up to brilliance as were thegreen lamps. The contact finger 64, now also in the fifth position,engages the short drum segment 83 and closes the group contactor |2 ofthe red lamps the group contactor |2 being thereafter maintained closedover a circuit made by the engagement of contact linger 65 with drumsegment 85 and thus` the red lamp circuit is prepared, and againvtheshunting eiect over resistance |16 is at a minimum through theengagement of contact nger 13 with drum segment 96.

In the sixth position the blue lamps 2 are fully lit and are transferredto the line, by engagement of drum segment |00 with contact finger 15.At the Sametime the green lamps 3 are, by disengagement of contactiinger 14 from drum segment 98 and the engagement of drum segment |03with contact finger 11, removed from the line and placed in series withthe booster which is, at this time, short-circuited by lengagement ofcontact finger 8| with drum segment |09, the shunting eiect ofresistance |16being again at a minimum owing to the engagement ofcontact finger 1| with drum segment 9|. The outer end contact of theregulator arm |20 is at this time travelling over regulator set D,accordingly, since the negative boost is not operative, the "green lamps3 remain at full brilliance.

As now the drum switch 63 completes its first revolution and moves intosection 1, the first position, the booster output is again brought up tomaximum by the increase of current through its shunt held winding |56,in the manner previously described, that is by movement of the reg-`ulator arm i2@ over the regulator set marked B;

accordingly the green lights are dimmed and the circuit therethrough 'isbroken on the disengagement of contact nger 11 with drum segment 03.Assuming the tumbler switch 41, to have been left in the closedposition, the group contactor it is held closed by a closing circuitmade through drum segment 39 and contact finger 68,

At the same time, a circuit is completed at contact finger 19, by theengagement therewith of the drum segment it', which inserts the redlamps i in series with the booster across the supply, the next movementof the drum switch and regulator will cause the red lamps to be broughtup to tell brilliance until, in position 2 the red lar s l are placeddirectly across the line by the engagement of contact finger i6 with thedrum segment mi. The blue lamps '12v are then, by the engagement ofcontact nger 18 with drum segment idd and the disengagement of drumsegment it@ from contact finger l5, transferred from the line and put inseries with the booster. booster is short-circuited at contact nger 8|,on drum segment i il, and the shunting effect of resistance L33 on thebooster is at a maximum owing to the engagement of contact inger 1| withdrum segment 92. The blue lamps 2 are subsequently dimmed.

Assuming that all the tumbler switches t5, 46, 41 are or remain closed,the cycle as described is continuously repeated, that is at any one timethev moment of transfer thel one colour is at full brilliance, one oft,and one fading in or out. [If` during operation any one of the tumblerswitches 45, 46, 41 is opened, the corresponding group contactor |2, |3,I4 willl be held closed until the associated lamp group has been dimmed.For example, if it is desired to cut out the` red lamps, the tumblerswitch 45 is opened, then with the drum moving towards position 5, theholding circuit through contact" `ilnger 65 and drum segment 85 will beeffective through coil 34 until position 5 is reached, then,

since with the tumbler switch 45 open the tem.

porary maintenance circuit through contact finger 64 and drum segment 83willbe open; coil 34 will be deenergized and the red" lamp groupcontactor |2opens, thus cutting out the group when the dimming circuitis at a maximum and most effective. Accordingly each group of lamps canonly be cut out of circuit when the current through themis substantiallyzero or so small as not effectively to illuminate them.

The stopping of the booster and the cutting out of the device iseffected by depression of the stop switch |48 which breaks themaintenance circuit through coil |95 of the booster contactor'v assembly(ISE-|91) and stops the booster motor, and the stop switch also cuts outthe booster circuit contactor |12.

It is of course to be understood that the arrangement, colours andgrouping of the lamps in the several groups may be anything desired, andthe number of groups may be varied according to requirements.

We claimtl. In an electric lighting system for changing the color schemeof lighting, a plurality of groups of colored lamps, circuits forlighting the groups from direct current bus-bars, individual switchesfor the bus-bar circuits of `the respective groups, a booster generatorhaving circuits arranged, to deliver current in opposition to thebus-bar current through the lamps, controlling means for operating therespective group switches and for controlling the bus-bar and booster,currents for lighting the groups of lamps in ,prearranged sequence,interlock contact means for the respective group switch circuitsarranged to cooperatev with the bus-bar and booster current controllingmeans so that the bus-bar circuits for the individual groups of lampsare opened and closed only at prearranged intervals in the applicationof the booster current, regulating means for automatically varying thebooster current for dimming the respective groups of lamps according toof colored lamps, circuits for lighting the lamp groups from constantpotential direct current bus-bars, electromagnetic switches for thebusbar circuits of the respective groups, a. booster generator capableof delivering current at the bus-bar potential, circuits arranged fordeliv-4 ering current from the booster in opposition to the bus-barcurrent through the lamps, a drum switch having contacts cooperatingwith circuits for controlling operation of said electro-magneticswitches and forV controlling the bus-bar and `the color scheme oflighting, a plurality of groups of colored lamps, circuits for lightingthe lamp groups from constant potential direct current bus-bars,electro-magnetic switches for the busbar circuits of the respectivegroups, a booster generator capable of`delivering current at the bus-barpotential, circuits arranged for deliveri ing current from the boosterin opposition to the bus-barl current through the lamps, a rotatabledrum switch having contacts cooperating with circuits for controllingoperation of said electromagnetic switches and for controlling the bus-,bar and booster circuits for lighting the respective groups of lamps inprearranged sequence, ro-

tatable regulating means provided with tapped rheostat and tappedcircuits for regulating the iield of the booster and varying thepotential of the booster current according to a prearranged cycle, and amotor for-rotating the drum switch and said regulating means in aprearranged cycle such that a varying booster current is applied to therespective groups of lamps in sequence in a repeating cycle.A

4. In an electric lighting system for changing the color scheme oflighting, a plurality of groups of colored lamps, circuits for lightingthe lamp groups from constant potential direct current bus-bars,individual electro-magnetic switches for'the bus-bar circuits of therespective groups, a booster generator capable of delivering current atthe bus-bar potential, circuits arranged to deliver current from thebooster in opposition to the bus-bar current through the lamps, arotatable drum switch having contacts cooperating with circuits forcontrolling operation of said electro-magnetic switches and forcontrolling the bus-bar and booster circuits for lighting the respectiveAgroups of lamps in prearranged sequence, contactors and circuitsassociated with the respective group switches and arranged to cooperatewith contacts controlled by the drum electro-magnetic switches so thatthe bus-bar circuits for the individual groups of lamps are opened andclosed and the booster current applied thereto at prearranged intervalsduring rotation of said drum switch, rotatable regulating means forautomatically varying the potential of the booster current and forvarying the dimming effect on the respective groups of lamps in aprearranged cycle and means'for continuously rotating the drum switchand said regulating means in predetermined ratio so that the dimmingeiect of the booster current is varied and applied to each group oflamps in succession in a repeating cycle.

5. In an electric lighting system for changing the color scheme oflighting, a plurality of groups of colored lamps, circuits for lightingthe lamp groups from constant potential direct current bus-bars,individual electro-magnetic switches for the bus-bar circuits of therespective groups, a booster generator capable oi delivering current atthe bus-bar potential, circuits arranged to deliver current from thebooster in opposition to the bus-bar current through the lamps, arotatable drum switch provided with contacts cooperating with circuitsfor operating the individual electromagnetic switches and forcontrolling the busbar and booster circuits for controlling the lightingof the respective groups of lamps in prearranged sequence, contactorsassociated with said. bus-bar switches having circuits cooperating withcontacts on said drum switch so that the bus-bar circuits for therespective groups of lamps are maintained closed and openedatprearranged intervals, said bus-bar switches being operated to open thecircuit only when the booster current is at `a minimum potential,regulating means for automatically varying the booster circuit forvarying the dimming effect on the respective groups of lamps according.to a prearranged cycle, said regulating means being provided with atapped rheostat and tapped shunting circuits for varying the potentialof the 'booster current, cooperating contacts associated with said drumswitch for cutting out the booster current and establishing circuits foroperating of the respective groups of lamps direct from the bus-bars,and means for rotating said drum switch and the regulating means inpredetermined ratio such that fory each rotation of the drum switch theregulating means is rotated as many times as there are groups of lamps,once for each group andthis prearranged cycle is repeated.

6. In an electric lighting system for changing the color scheme oflighting, a plurality of groups of colored lamps, circuits for lightingthe lamp groups yfrom constant potential direct current bus-bars,individual electro-magnetic switches for the bus-bar circuits of therespective groups, a booster generator capable of delivering current atthe bus-bar potential, circuits arranged to deliver current from thebooster in opposition to the bus-bar current for dimming the lamps, adrum switch provided with contacts cooperating with circuits foroperating the individual electromagnetic switches and for' controllingcircuits of the vbus-bar and booster for controlling the lighting of therespective groupsv of lamps in prearranged sequence, regulating meanscomprising a tapped rheostat and tapped iield excitation controllingcircuits for automatically varying the potential of the booster currentto effect dimming of the respective groups of lamps according to aprearranged cycle, said circuits for controlling the booster eld beingassociated with contacts on the drum switch arranged for operation in aprearranged cycle for controlling the iield excitation of the boostergenerator, certain of said circuits and contacts being arranged toestablish a small reverse excitation in the iield winding of the boostergenerator during a portion of the dimming cycle, and means for rotatingthe drum switch and said regulating means in predetermined ratio, suchthat each group of lamps is dimmed in succession foreach rotation of thedrum switch.

BASIL DAVIS. GEORGE ELLIS. HERBERT JOHN COATES.

